CarbohydratePolymers 110 (2014) 309–319 Contentslists availableat ScienceDirect Carbohydrate Polymers j o u r n a l h o me p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c a r b p o l Influence of plasticiser on the barrier, mechanicaland grease resistance properties of alginatecast films Verena Jost a,b,∗ , Karin Kobsik a , Markus Schmid a,b , Klaus Noller a a Fraunhofer Institute for Process Engineering and Packaging IVV, Giggenhauser Strasse 35,85354Freising, Germany b Chair of FoodPackaging Technology, Technische Universität München, Weihenstephaner Steig 22,85354Freising, Germany a r t i c l e i n f o Articlehistory: Received6 September 2013 Receivedin revisedform 5 March 2014 Accepted31 March 2014 Available online 8 April 2014 Keywords: Alginate Plasticiser Mechanical properties Barrier Oxygenpermeability Water vapour transmissionrate a b s t r a c t Alginatecastfilms were plasticised by two plasticisers – glycerolandsorbitol – in differentconcentrations. As a function of the plasticisertypeand concentration, the following parameters were investigated: equi- librium moisture content (EMC), colour measurement, microscopic analysisby SEM, greaseresistance, oxygenpermeability(OP), water vapour transmissionrate (WVTR) and the mechanicalproperties.Both plasticisershavea positive influenceon the mechanical propertiesbut differ in their effecton the barrier properties.Whilst an increasingconcentrationof glycerol increases the permeabilityof alginatefilms to oxygen and water vapour, sorbitol did not influence the barrier properties to oxygen or water vapour. The behaviourof glycerol is in accordance with the free volume theory. The effect of sorbitol is assumed to be due to the good steric fit of sorbitol into the alginate network. The good embedding of sorbitol betweenthe alginatepolymer chains meansit can lower the intermolecularbonding while still offering bonding possibilities.Thereforethe flexibility of the castfilms is increasedwhile maintainingthe barrier properties. ©2014 Elsevier Ltd. All rights reserved. 1. Introduction With the aim of creating a sustainable packaging material for sensitive products, efforts have been made to develop materials based on renewable resources rather than petrochemical-based materials. The requirements of packaging materials depend on the packed goods. The packaging materials need to fulfil different needs in terms of moisture and grease resistance as well as the water vapour and gas barriers. In order to create a packaging concept for optimal preservation of the packed goods, for example foods, different parameters such as the barrier and mechanical properties, packing atmosphereand the transpiration and respiration rate of the food must be taken into account in order to avoid loss of nutritional content, off-flavours, colour changes, oxidation processesand spoilage.In order to meet these requirements, multilayer structures based on polymer or paper substrates are widely used in the packaging industry. These ∗ Correspondingauthor. Tel.: +498161491 227; fax: +498161 491 555. E-mail address: Verena.Jost@ivv.fraunhofer.de (V. Jost). structures consist of materials with the requisite functional properties combined by co-extrusion or lamination (Mueller, Schoenweitz, & Langowski, 2012; Petersen et al., 1999). Within these structures, ethylene vinyl alcohol copolymers (EVOH) are commonly employedto createan adequate barrier againstoxygen. Besides EVOH, the polymers used for this application are almost always petrochemical-based. Another aspect is the recyclability, which is often not possible for thesemultilayer structuresbecause separation into the pure materials is difficult (Bugnicourt et al., 2013; Endres & Siebert-Raths, 2011; Schmid, Hinz, Wild, & Noller, 2013). By using bio-based and biodegradablematerials in such a system,the dependenceon petrochemical-based materials can be reduced and a solution for the recycling process can be provided. Thus research on biopolymer packaging materials has recently intensified. To accelerate the developmentof bio-based and biodegradable polymers,various attemptshavebeenmadeto improve the proper- ties of carbohydrates, proteins and evennatural waxes(Chiumarelli & Hubinger, 2014; Janjarasskul,Rauch,McCarthy, & Krochta, 2014; Mekonnen, Mussone, Khalil, & Bressler, 2013; Rodrigues et al., 2013; Schmid et al.,2013).The presentarticle focuseson alginate, a http://dx.doi.org/10.1016/j.carbpol.2014.03.096 0144-8617/©2014 Elsevier Ltd. All rights reserved.